Heretofore, for improving the water- and oil-repelling properties of substrate surfaces, it has been a known practice to coat silicon-based surface active agents onto substrate surfaces or fluorocarbon-based polymer suspensions onto substrate surfaces.
Generally, a material with a fluorine resin coating is obtained by making the surface coarse by means of electrolytic etching or surface roughening to increase adhesion with a fluorine-based polymer. The surface is coated with a fluorine-based polymer suspension, followed by baking.
The prior art substrate is generally known to exhibit improved water- and oil-repelling properties and can be readily manufactured. However, if the film coating on the substrate surface is insufficiently thin, it results in generation of pin holes, so that sufficient water- and oil-repelling properties can not be obtained. In addition, even if the film coating is sufficiently thick, its water- and oil-repelling properties are sometimes inadequate.
Furthermore, where a water-repelling oil-repelling film is provided on a transparent substrate such as a glass substrate, the transparency thereof is deteriorated due to the film thickness that is needed.
In addition, the surface and fluorine-based polymer coating are weakly coupled together for there are no chemical bonds between the two. Therefore, when the material is used for a substantially long time, the adhesion deteriorates resulting in a separation of the fluorine-based coating from the surface of the material.
Therefore, a material with a fluorine-based coating which is substantially free of pin holes, is uniform in thickness, and has excellent water- and oil-repelling properties is highly desirable.